Well, perhaps a lava bender OC fanfiction where the character discovers an ancient lava bending technique that was long forgotten. This discovery could put them in a dangerous situation as others might want to steal the knowledge. They could also be in a love story where their lava bending plays a role. For example, they create beautiful lava sculptures for their love interest. Or they might have to use their lava bending to save their love from a natural disaster related to volcanic activity.
One idea could be a lava bender OC who is an outcast in their village because their lava bending is too powerful and they struggle to control it. They then go on a journey to find a master who can teach them control. Another could be a lava bender OC in a war, using their unique abilities to turn the tide of battles. Maybe they can create lava barriers to protect their allies or use molten rock to destroy enemy fortifications.
One interesting plot could be a character with the lava bloodline being ostracized at first because others fear their power. Then, they prove themselves by using their unique abilities to save the village from a powerful enemy.
For an Avatar Water Bender OC fanfiction, consider this plot. The OC is a water bender who has the ability to communicate with water spirits in a way no one else can. A dark force is starting to corrupt the water spirits, and the OC must go on a quest to find out what is causing this and stop it. Another idea is that the OC is an outcast in their water tribe because they have a different way of water bending. They leave the tribe to prove themselves and end up joining a group of rebels fighting against an oppressive regime. And yet another plot could be that the OC discovers a secret underground water source that has special properties, and they have to protect it from those who want to use it for evil purposes.
One plot idea could be that a lightning bender ninja is tasked with protecting a secret scroll that contains ancient knowledge about lightning - based jutsu. Enemies from other villages are after this scroll, and the ninja has to use their unique skills to fend them off. This could lead to epic battles and strategic maneuvers.
One idea could be a character who discovers they have blood - bending abilities in the Naruto universe and has to hide it from their village at first. Maybe they are from a non - water - based village and fear being ostracized. Another plot could involve a blood - bender using their power to heal instead of harm, which goes against the traditional view of blood - bending in other fictional universes. A third idea might be a blood - bender who gets caught in the middle of a war between two great ninja powers and has to decide which side to use their power for.
Start with their backstory. Maybe they come from a family of lava benders and have a long line of traditions. Or they could be the first in their family to discover this ability. Consider their personality. Are they hot - tempered like the lava they bend? Or are they calm and collected, using their power with precision. Also, think about their goals. Is it to become the most powerful lava bender? Or to use their power for the good of their community?
One idea could be Naruto being turned into a girl and having to deal with different social expectations in the ninja world. For example, she might face more restrictions in combat training at first because of the traditional gender roles. Another plot could involve the reactions of his friends like Sasuke and Sakura. Sasuke might be more protective or have a different dynamic with a female Naruto.
One idea could be that Naruto is turned into a girl by a strange jutsu accident. The members of his harem could include Sasuke, who is now intrigued by this new Naruto, and Sakura, who becomes more protective. Another could be that Naruto enters a new dimension where gender roles are reversed for everyone, and he has to navigate this new world while building his harem.
Another plot could revolve around an OC who is a Spartan trainee that doesn't quite fit the mold. They have a different way of thinking and approaching combat. In Halo 4, they end up being the key to solving a mystery related to the Prometheans. Maybe they find a way to communicate with the Prometheans and convince some of them to stop fighting the humans.
One idea could be an Otsutsuki OC who comes to Earth not for conquest but to study the unique life forms here. They could befriend some of the local ninjas and learn about the concept of friendship, which is alien to the Otsutsuki. This would lead to a series of adventures where they have to protect their new friends from other more hostile Otsutsuki members.
One idea could be an OC who is a long - lost relative of Moana. This OC could have been separated from the family during a great storm years ago. They could have unique skills, like being able to communicate with a different type of sea creature that Moana has never encountered. This would bring new adventures as Moana and the OC try to figure out how this new discovery could help their island.